Apparatus for testing well formations

ABSTRACT

An apparatus is provided for obtaining a test sample of formation fluids from a well bore formation. An elongated tool is lowered into a well bore and is provided with explosive means for perforating the casing and formation at a desired production site. Sealing means is incorporated on the tool to define an isolated, relatively large diameter fluid flow path from the perforated formation site to a formation fluid receiving, test sampler chamber disposed within the tool. A unitary slide valve arrangement is provided within the tool for sequentially closing the fluid sample test chamber and equalizing the pressure differential across the sealing means to release the sealing means from the formation and permit the overall tool to be withdrawn from the well bore. The slide valve is powered by pressures existing in well bore fluid ambient to the tool.

United States Patent [72] Inventor Orville Roland Smith 3,385,364 5/1968Whitten 166/100 Houston, Tex. 3,530,933 9/1970 Whitten I66] 100 1970Primary Examiner.lames A. Leppink M Ill Patented d. 1971 Attorney Burns,Doane, Benedict, Swecker & a [73] Assignee Halliburton Company nunumokhABSTRACT: An apparatus is provided for obtaining a test sample offormation fluids from a well bore formation. An [54] APPARATUS FORTBS-"N6 WELL FORMATIONS elongated tool is lowered into a well bore andis provided with 12 Claims 10 Drawing 8% explosive means for perforat ngthe cas ng and formation at a desired production site. Sealing means isincorporated on the [52] US. Cl 166/55.l, too] to d fi an isohedrelative, use diameter fl id fl 166/100 path from the perforatedformation site to a formation fluid [51] lnt.Cl E21b33/l2 receiving testchamber disposed within he tool A Field of Search 166/100, unitary Slidevalve arrangement is Provided within the tool f sequentially closing thefluid sample test chamber and equalizing the pressure differentialacross the sealing means to [56] References CM release the sealing meansfrom the formation and permit the UNlTED STATES PATENTS overall tool tobe withdrawn from the well bore. The slide 3,253,654 5/1966 Briggs, Jr.et a]. 166/100 valve is powered by pressures existing in well bore fluidam- 3,430,i8l 2/1969 Urbanoskv 166/100 bient to the tool.

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PATENTED OCT 5 ISH SHEET 1 OF 4 INVENTOR ORVILLE ROLAND SMITH Rams,180m, Puum'at, [Ia/awn MRI/:8

ATTORNEYS APPARATUS FOR TESTING WELL FORMATIONS BACKGROUND OF THEINVENTION The invention relates generally to the testing of earthformations intersected by a well bore and more specifically relates to anew and improved apparatus for conducting such testing operations from ahoisting cable or "wire line."

Currently, formation testing tools are being employed having at leastone sealing member or "pad" which is urged into engagement with a wellcasing or formation face and which functions to define an isolated flowpath from a formation perforation developed adjacent the sealing meansto a formation fluid receiving chamber within the tool. The perforationwithin the formation may be formed by an explosive charge carried by thetool and electrically detonated. The perforating action of the chargemay be augmented by providing a metallic man to be propelled into thefonnation or, alternatively, the perforation may be developed merely bythe blast effect of a shaped charge.

Once the formation fluid seal is set, fluid flows through an isolatedpath from the formation perforation site to the sample receiving chamberwhich may be located anywhere within the tool but is preferably disposedat the top or bottom thereof. After a desired volume of formation fluidhas been obtained, the sample receiving chamber is closed off from theisolated flow path and the sealing member is released so that theoverall tool may be withdrawn from the well bore by a cable and taken tothe surface of the well site so that the sample may be removed from thetool to be measured and analyzed.

While complex and multiple valve arrangements in tester tools have beenproposed to effect the sequence of operations above described, sucharrangements have, in general, lacked the desired structural simplicityand operational reliability.

A common problem associated with perforation type, fluid samplingoperations involves the fact that well formations are many times poorlyconsolidated. Thus, formation fluid comprising a sample may containlarge amounts of detritus and/or sand. Such detritus and/or sand, oncewithin a tester tool, tends to block the various flow passageways withinthe tool, erode various parts thereof, and jam the members, the movementof which may be necessary to the proper functioning of a cable-hoistedtesting apparatus.

Additionally, prior attempts to incorporate the several necessaryfunctions of a sample tester tool within one device have often resultedin complicated and expensive equipment. Many prior testing tools havebeen characterized by an excessive number of moving parts andundesirable bulk.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of thepresent invention to provide a new and improved apparatus for testingthe production fluids of earth formations.

It is another object of the present invention to provide an apparatusfor obtaining a sample of a formation fluid, which apparatus reduces thedetrimental effects of any sand or detritus entrained within such fluid.

It is still another object of the present invention to provide anapparatus for testing formation fluids, which apparatus is lesscomplicated than prior apparatus.

It is yet another object of the present invention to provide anapparatus for testing formation fluids wherein the single movement of asingle member results in the sequentially controlled performance of aplurality of vital functions within a tester tool.

It is a further object of the present invention, in the context of theforegoing objects, to provide an apparatus for testing formation fluidswherein well bore fluid pressure is utilized as a power source so thatonly minimal stored energy need by carried by the tester tool itself.

It is still a further object of the present invention to provide anapparatus for solving many of the problems encountered in obtainingsamples of formation fluids using cable-hoisted testing tools.

The objects of the present invention may be achieved by providing aformation testing tool having means carried therein for perforating theside of a well and the formation adjacent thereto. Sealing means isprovided for defining an isolated flow path leading from the perforationsite to the interior of the tool wherein a formation fluid samplereceiving chamber may be disposed. A single, unitary valve means isprovided within the tool to sequentially seal the formation fluid samplereceiving chamber and release the sealing means from the bore casing sothat the tool may be withdrawn from the well bore.

Ambient, well bore fluid pressure may be utilized to power the movementof the valve means in a unique, two-stage manner.

Additional means may ing the valve means.

BRIEF DESCRIPTION OF THE DRAWINGS While the invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification, preferred and alternative embodiments of the presentinvention are described in the following specification. which may bebest understood when read in connection with the accompartying drawingsin which:

FIG. 1 shows an elevation pictorial view of a preferred embodiment ofthe present invention disposed within a well bore;

FIG. 2 is a partial sectional view of a tool decentralizing springassembly taken along the longitudinal axis thereof, with reference tosection line 2-2 of FIG. 3;

FIG. 3 is a sectional view of the decentralizing spring shown in FIG. 2taken along the line 3-3;

FIG. 4 is a detailed, partial sectional view of the apparatus shown inFIG. 1 taken along the longitudinal axis thereof, with tool portionsshown in axially spaced relation;

FIG. 5 is a sectional view of a formation fluid sample chamber closingand pressure equalizing valve portion of the apparatus shown in FIG. 4wherein the sample chamber is in fluid flow communicating relation witha formation perforation;

FIG. 6 is a sectional view of the apparatus shown in FIG. 5 immediatelyafter actuation of the sample chamber closing and equalizing valvemechanism, wherein the sample chamber has been sealed but the pressuredifferential between the inside and outside of the overall tool has notyet been equalized;

FIG. 7 shows the valve mechanism of FIGS. 5 and 6 sequentially alter thevalve mechanism has traveled the full stroke wherein the samplereceiving chamber has been sealed and the pressure outside the tool hasbeen communicated to the space within the tool so as to equalize the twopressures;

FIG. 8 is a sectional view of the apparatus shown in FIG. 4 taken alongthe line 8-8;

FIG. 9 is a sectional view of the apparatus shown in FIG. 4 talten alongthe line 9-9, and

FIG. 10 is a cross-sectional view of an alternative embodiment of thevalve mechanism of the present invention shown in FIGS. 5, 6 and 7 takenalong the longitudinal axis thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OVERALL TOOL Referringnow to the drawings in which like numerals are used to indicate likeparts throughout the various thereof, FIG. I shows a pictorial view of aformation testing tool which may be lowered on a cable (not shown). Thetool is inserted within a well bore 10, which may be defined by a wellcasing 12. The cylindrical interior surface of the casing 12 isdesignated by the numeral l3.

The upper end of the tool is provided with a fitting 16 which serves asa "wire line" or cable connector. A formation fluid sample receivingchamber section 18 may be disposed immediately beneath and adjacent thecable connector. As

he provided for hydraulically openshown in FIG. I, an upper adaptersection 17 may be used to connect the fitting 16 with the fluidreceiving chamber section 18. An explosively actuated valve section 20is disposed between the sample receiving chamber 18 and a lower,perforator and sealing pad carrier section 22.

Sealing pads 24 are mounted on the outer surface of the carrier section22 adjacent the explosive charges (not shown) which may be electricallyactuated to perforate the formation 14 through the well casing 12. Thetool shown in FIG. 1 has two such sealing devices aligned with a commonlongitudinal plane such that two perforations will be blasted into theformation 14. it should be understood, however, that any number ofperforations may be formed using the apparatus of the preferredembodiment.

LOWER END OF TOOL A tool decentralizing, spring apparatus 26 is attachedto the lower end of the tool and operates to urge the sealing members 24into sliding engagement with the surface 13 of the well casing I2.

The operation and detailed structure of the operating spring 26 may bestbe understood when described in connection with FIG. 2. The function ofthe decentralizing spring 26 is to bias the sealing pads 24 shown inFIG. 1, against the side 13 of the casing 12 so as to position aperforating shaped explosive charge in proper alignment with a site tobe perforated. In order to bias the overall tool toward one side of theinternal surface 13 of the casing 12, two bowed leaf springs 30 aremounted on a shaft 32 and extend in a generally longitudinal directionwith respect to the tool. Leaf springs 30 are circumferentially spaced120 from each other and from the longitudinal median plane of sealingpads 24. The upper end of the shaft 32 is formed with male threading 34which engages within female threading 35 (see FIG. 4) formed on thelower portion of the carrier section 22 of the main body of the overalltesting tool. A collar member 36 is also threadedly mounted on the malethreads 34 of the axial shaft 32 and provides an anchoring point atwhich the upper ends of the leaf springs 30 are connected to the axialshaft 32 by means of threaded fasteners 38.

The decentralizing apparatus shown in FIG. 2 is adapted to bias the toolconnected thereto to the right, as shown in FIG. I.

The lower end of the leaf springs 30 are connected to a slidable collarmember 42 by means of threaded fasteners 44. When the tool is in a wellbore, the center, bowed portion of springs 30 will thus yieldablyflatten or radially contract and assume the phantom line configurationshown in FIG. 2. This flattening will be permitted by the slidablecollar 42. Phantom lines 46 indicate the contracted configuration of thebowed leaf springs 30 and phantom line 48 indicates the position of thecollar member 42 when the leaf spring is forced into a configurationindicated by the aforementioned phantom lines 46.

A bull plug 54 may be threadedly engaged on male threads 56 formed onthe lower end of the decentralizing spring shaft 32. The purpose of thebull plug 54 is to present a generally pointed leading edge for theoverall tool so as to facilitate movement of the tool into and throughthe well bore.

MAIN BODY OF TOOL Referring now to FIG. 4, details of the main body ofthe tool are shown in three axially separated views of tool bodyportions. As will be understood, the length of the tool may vary,depending on the length of tool cylinder walls connecting the portionsshown in these views.

The Iefimost portion of FIG. 4 shows the threaded end 34 of the axialshaft 32 of the decentralizing spring arrangement 26. As can be seen,the threaded portion 34 engages within female threading 35 formed withina lower portion of the carrier section 22 of the overall tester tool.Shaped charges 60, each one associated with each pad 24, are disposedwithin the lower section of the carrier member 22. Each charge 60 isprovided with a rearwardly extending conical projection 62. The conicalprojection 62 fits within a recess 64 which corresponds in configurationto the surface shape of projection 62 and is formed within the interiorwall 66 of the carrier section 22. The forward end of the shaped chargeis provided with a gun barrel-like stud 68 which extends through thewall of the carrier section 22 and is provided with a wide head portion70 for impingingly securing a sealing member 24 against the outersurface 71 of the carrier section 22 of the overall tool.

Each sealing member or pad 24 consists of a flexible elastomericsubstance such as natural or synthetic rubber and is generallyconfigured as an annular body, curved about the exterior of the carriersection 22. Each pad 24 slides along surface I3 when inserted within thewell bore 10.

A rigid metallic disc 72 may be embedded within each sealing member 24as shown in FIG. 4. A frustoconical sealing nose portion 70 of astudlike, barrel member 68 of the shaped charge 60 engages the disc 72as shown in FIG. 4. Pin members 74 are mounted within the metallic plate72 and extend normally therefrom into recesses 76 formed within the wallof the carrier section 22. The pin members 74 function to ensure theproper positioning of the seal member 24 and cooperate with therearwardly extending conical projection 62, which fits within the recess64, to properly align the shaped charge and barrel-like stud 68.

OPERATION OF THE PERFORATION AND SEALING MEANS The overall tool islowered into the well bore I0 by means of a cable (not shown). Upon theproper vertical positioning of the shaped charges 60 and sealing members24 adjacent a site to be perforated, a conventional firing mechanismshown generally in FIG. 4, is actuated and the shaped charges aredetonated. The shaped charges 60 may be detonated by means of anelectrical system of which electrical conductors 75 comprise a portion.Upon detonation of the charges 60. the nose portions '70 of thebarrel-like studs 68 are punctured by shaped charge blasts. The productsof the explosion then puncture the well casing I2 and penetrate deeplyinto the for mation adjacent thereto.

The well bore fluids in the annulus surrounding the overall tool and thesealing member 24 are under a much higher pressure than are theformation fluids. Consequently, a pressure differential develops whichurges the carrier 22 against the perforation site, causing the pads 24to form seals encircling the formation perforation sites.

The formation fluids are than permitted to flow out from the formationand through the central apertures formed in the nose portions 70 by thedetonation of the shaped charges. Since the charge explosions demolishall the structures designated as 60, the formation fluids will flowthrough the barrel-like stud members 68 and into the space 82 within thecarrier section 22 of the too].

As can be seen by a perusal of the central drawing of FIG. 4, more thanone perforating charge and sealing member combination may be provided ineach testing tool. Since it is important to develop a pressuredifferential vector operating in a single general direction to obtainproper sealing, it is important that all the sealing members 24 bearranged on a generally vertical line. Likewise, since the differentialpressure draws the sealing means and the tool closer to the casing alonga vertical line, it is preferred, although not absolutely necessary.that the shaped charges be simultaneously detonated to get the greatestsimultaneous impact obtainable.

Tracing the valve section of overall tool now from the lower carriersection 22 into the sampling receiving chamber sealing and pressureequalizing valve section 20, it will be noted that a rough filter member86 is provided at the juncture between the sections 22 and 20. The upperend of the carrier section 22 is formed with female threading 88 and thelower portion of the valve section 20 is formed with male threading 90.Threadings 90 and 88 are matingly engageable to provide a rigidconnection between sections 20 and 22. The rough filter member 86 isformed with a male threading 92 at the upper end thereof for threadedengagement within female threading 94 formed within the lower end of thevalve member section 20.

A relatively thin walled, slidable hollow valve stem 100 is disposedwithin an axial passageway 102 of the valve section 20. Axial passageway102 provides communication through relatively large passageway 103,defined by the hollow stern 100, between the space within the carriersection 22 and the formation fluid receiving sampler chamber 104. Thiscommunication is achieved through radial ports 106 formed near the upperend of the valve stem member 100 and communicating with passage 103.When the stem 100 is in the raised position shown in FIG. 4, the ports106 are disposed in and communicate with the interior of chamber 104.

The passageway 102 is widened along a portion thereof intermediate ofits length to form cylindrical surface 110 which defines an annularspace 111 about the valve stem 100, It is apparent that, with the valvestem 100 in the position shown in FIG. 4 the formation fluids enteringthe space 82 defined by the casing of the carrier section 22 will flowfrom the formation (which is at a higher pressure than the atmosphericpressure within the tool) through the rough filter 86, through the axialfluid passageway 102 of the valve section 20, through the axial fluidpassageway 103 of the valve stem member 100 and radially through theports 106 thereof into the reservoir space 105 defined by the formationfluid sampler receiving chamber 104.

The portion of FIG. 4 at the far right-hand side of the sheet shows theupper portion of the formation fluid receiving chamber 104 which isprovided at an upper end thereof with a second rough filter member 113.The upper axial portion of the chamber 104 is formed with female threads117 which matingly engage with male threads 119 formed on the loweraxial end of the upper adapter section 17. The filter 1 13 is providedwith threads 121 to engage with threads 170 formed in the lower axialend of section 17. A passageway 123 is defined within the upper adaptersection 17 from the filter member 1 13 to the outside surface 1 15 ofthe upper adapter section 17 at an outlet site 125. A plug member 116 isthreadedly secured within the passageway 123 and may be removed from thepassageway by a conventional tool to permit the formation fluids to beremoved from the sampler chamber after releasing and withdrawing theoverall tool from the well bore 10.

The outer cylindrical surface of the stern 100 is formed with astepped-up or radially enlarged cylindrical portion 108 which fitswithin the annular space 11 formed intermediate the axial ends of thepassageway 102. The valve body for housing the valve stem 100 comprisesa cylindrical mandrel 112. Mandrel 112 may be connected at its lowermostend with an adapter member 114 by means of female threads 116 on thelower end of the mandrel and male threads 118 on the upper end of theadapter member 114. The adapter member 114 defines the lower end ofsection 20 and is connected with carrier section 22 as previouslydescribed.

It will be noted, that the composite axial passageway formed through themandrel member 112, being of reduced diameter near the upper endthereof, forms an internal annular shoulder 120. The reduced diameter ofthe mandrel corresponds to the outside diameter of the nonstepped-up, ormain cylinder wall portion of the valve stem 100. The adapter portion114 is similarly formed with an axial passageway having a diametercorresponding to the outside diameter of the lower, nonstepped-upportion of the valve stem 100.

OPERATION OF THE SAMPLER RESERVOIR SEALING AND PRESSURE EQUALIZING VALVEWith the above-described configuration of valve stem 100 within themandrel 112 and adapter member 114, it is apparent that, when the valvestem is in the FIG. 4 position, to expose the radial ports 106 to theinterior of the sample receiving chamber 104 of the overall tool, theupper radial surface 122 of the stepped-up portion of the valve stem isin abutting relationship with the annular shoulder of the mandrel member112. The portion of the axial passageway 102 through the mandrel member112 extending downwardly from the annular shoulder 120 to adjacent theupper end of the adapter member 114 is of a diameter corresponding tothe outside diameter of the cylindrical stepped-up portion 108 of thevalve stem 100. Therefore, it is apparent that, when a sufficient,downwardly directed, axial, hydraulic force is applied to the radialsurface 122 of the stepped-up portion 108 of the valve stem 100, theoverall valve stem may be axially moved downward until the lower radialsurface 124 of the built-up portion 108 comes into abutting relationshipwith an upper radial surface 126 of the adapter member 114.

The force necessary to move the valve stem 100 downwardly, so as to sealoff the passageway 103 defined therethrough from the interior of thesample receiving chamber 104 by withdrawing radial ports 106 to withinthe upper axial passageway 102 of the mandrel member 112, may beprovided by directing high-pressure annular fluids from outside the tooland through a generally axially extending passageway 128 against theupper radially extending surface 122 of the built-up portion 108 of thevalve stem 100. In order to supply the high-pressure annular fluid tothe generally axially extending passageway 128 a second passageway 132,shown in FIGS. 1 and 8 is formed in the body of the mandrel member 112and extends in a radial plane thereof from the up per-most end of thepassageway 128 through the outer surface 130 of the mandrel member 112.

FIG. 8 is a cross sectional view of the mandrel member 112 taken alongradial line 8-8 of FIG. 4 which lies in the plane containing theabove-mentioned second passageway 132. It can be seen from this viewthat a plug member 134 is threadedly engaged within the passageway 132by means of male threads 136 on the plug member 134 and female threads138 formed within the passageway 132. An explosive squib member 140 isretained within a cylindrical recess 142 formed within the plug member134. Electrical detonating wires 142a lead from the rear portion of theexplosive squib 140 through a passageway 144 also extending in theradial plane containing the passageway 132 and defined by the sectionalline 8-8 of FIG. 4. An electrical junction 146 is connected to the otherend of the detonating wires 1420, which electrical junction is retainedwithin a radially extending recess 148 formed in the outer surface 130of the mandrel member 112. Wires 1S0 lead from the electrical junction146 axially upward along the outside of the overall tool up throughpassageway 151 formed in upper adapter member 117 (see FIG. 4) andthrough the well bore 10 to an operator's position on the surface of thebore site (not shown).

Upon of the explosive squib 140, the plug member 134 is ruptured andwell annulus fluid surrounding the outer surface 130 of the mandrelportion 112 of the overall tool rushes into the passageway 132 and downvertically through the connecting passageway 128 to encounter and actupon the upper radially extending surface 122 of the stepped-up portion108 of the valve stem 100.

The sequence of operation of the valve stem may be best understood byreference to FIGS. 5, 6, and 7. FIG. 5 shows the valve stem 100 in theuppermost position corresponding to the position of the stem in FIG. 4.The ports 106 are exposed to the internal space defined by the formationfluid sampling chamber 104 so that formation fluids may flow upwardlythrough the central passageway 103 of the stern 100 and radially outwardthrough the ports 106 into the space defined by the sample receivingchamber 104.

When the squib 140 is detonated, the passageway 132 is opened and thehigh-pressure annular fluid flows through this passageway axiallydownwardly through the passageway 128 to act upon the surface 122 of thestepped-up portion of the valve stem 100. The force developed by thepressure of the annular fluids on the area of the radially extendingsurface 122 forces the stem 100 away from the formation fluid receivingsampling chamber so that the ports 106 of the stem I become blocked bythe internal surface 153 of the axial passageway formed through themandrel 112. At this point, the flow path of formation fluids to thesample receiving chamber is sealed closed and the fluids retained withinthe formation fluid sampler chamber become isolated. This point in thesequence of valve operation is illustrated in FIG. 6 of the drawing.

As the higlrpressure annular fluids continue to flow through theexplosively opened passageways I32 and 128 and continue act upon thearea of the radial surface 122 of the stepped-up portion 108 of thevalve stem 100, a second passageway 152 formed in the mandrel member 112of the valve body communicates the high-pressure annular fluids with theannular space I 1 I adjacent the area defining the radially extendingsurface 122 of the built-up portion 108 of the valve stem 100. This isshown in FIG. 6 of drawings.

As the outer cylindrical surface 154 of the built-up or radiallyenlarged cylindrical portion 108 of the valve stem I00 clears theradially extending passageway I52, additional annular fluids arepermitted to flow through passageway 152 into the annular space 111adjacent the radially extending surface 122. While passage means 128 and132 are somewhat small due to their location in the tool, and might bevulnerable to partial plugging, passage 152 is relatively large,continuously open, and not likely to become clogged. In the preferredembodiment of the present invention the radially extending port I52 isseveral times larger in cross-sectional area than either of the portsI28 or 132 and provides a relatively unobstructed, high-capacitycommunication path between the well bore and the space I] I. Thepressure drop across port 152 should thus not be as great as thepressure drop across port means 128-132.

In efl'ect, the detonation of the squib I40 and the direction of thehigh-pressure annular fluids through the mandrel I12 and against thearea of the radial surface 122 of the valve stem I00 is a startingoperation which begins the movement of the valve stem I00 away from theformation fluid sampler chamber 104. The force applied to the surface122 only need be great enough to move the outer cylindrical surface 154of the stepped-up portion I08 of the valve stem 100 to a position clearof the large axially extending port I52 formed in the mandrel member 112of the valve body.

As shown in FIGS. 4, 5, 6, and 7. an additional radially extending port156 is formed through the valve stem I00 and is positioned tocommunicate with the annular space 111 when the radial extending surface124 of the stepped-up portion 108 of the valve stem 100 is in abuttingrelationship with the radially extending surface I26 of the adaptermember at substantially the full stroke of the valve stem 100. Althoughthe preferred embodiment shown in FIG. 7, shows the port 156 alignedwith the radially extending passageway I52 at the full stroke of thestem 100, it is only necessary that the port 156 is moved sufficientlyaway from the formation fluid receiving sampler chamber 104 so as toclear the internal shoulder I24 and communicate with the annular space111. In this manner, high-pressure, hydrostatic-Le. annulus, fluidrushed in through the radial passageway 152 in the mandrel I12 as thecylindrical surface 154 of the stepped-up portion of the valve stem I00clears the port 152. Then the high-pressure well annulus fluid rushesinto the annular space I11 defined by the cylindrical surface 158 of thenonstepped-up portion of the valve stem I00 and the internal surface 110of the axial passage I02 within the mandrel member In which cylindricalsurface 158 has a diameter corresponding to the diameter of thestepped-up portion I08 of the valve stem I00.

With the valve stem in FIG. 7 position, the high-pressure annulus fluidis then free to flow through the additional port 156 formed within thevalve stem 100. Since the terminal portion of the upper axial end of thestern passageway I03 is blocked by a radially extending wall 157, thehydrostatic fluid can only flow downwardly through the axial passagewayI03 of the valve stem into the axial passageway 102 formed through theadapter member I14. Therefore. the movement of the valve stem 100 to aposition where the upper radial ports I06 become blocked by the internalcylindrical surface 153 results in the flow of hydrostatic fluid beingdirected to the carrier section 22 end of the tool.

Referring back to FIG. 3 of the drawings, it will be understood that thehigh-pressure annular fluids will flow through carrier 22 toward theperforation sites. It will be remembered, that the sealing members 24are forced against the perforation sites by the difi'erential pressureacting across the tool, which diflerential pressure is a resultant ofthe high-pressure annular fluids on the tool side of the sealing padsand the low-pressure formation fluids on the other side of the pads.However, as the high-pressure annulus fluid flows down through theinterior of the tool and out through the isolated flow paths and intothe formation perforations, the presure differentials across the sealingpads 24 are eliminated so that the sealing effect of the sealing padsaround the perforation sites is released. The overall tool may then becable hoisted out from the well bore I0 to the surface of the well site.Once the tool is recovered, the formation fluid sample may be withdrawnfrom the formation fluid sampler reservoir 104 in a manner which willnow be described.

Still referring to FIG. 4 and in particular to the portion of the figurerepresenting the uppermost end of the overall tool, the passageway 123will be noted to extending from the upper end of the formation fluidsampler reservoir I04 and through the outer surface of an upper adaptermember 17 upon which a cable coupler member 16 may be mounted. The plug116, which is threadedly engaged within the passageway 123 so as toblock the passage of fluids therethrough. may be removed by a tool sothat the formation fluid sample within the reservoir I04 may be removedfrom within the reservoir.

BRIEF SUMMARY OF THE OVERALL OPERATION OF THE PREFERRED EMBODIMENT OFTHE PRESENT INVENTION In operation, the overall tester tool is loweredinto the well bore 10 by means of a hoisting cable. When the sealingpads 24 become disposed adjacent a formation site to be perforated, theexplosive charges within the tool and behind each sealing pad aredetonated. The detonation perforates the well casing I2 and penetratesdeeply into the formation. The fluids in the formation being at asubstantially lower pressure than the high-pressure hydrostatic annularfluids surrounding the tool, a pressure differential is developed whichcauses sealing members 24 to sealingly engage the casing whileencircling the perforation sites. This pressure differential secureseach sealing member around each perforation so that an isolated flowpath is formed between the formation fluid and the interior of theoverall tester tool.

The formation fluid then flows upwardly through the axial path I02defined through the various members comprising the overall tool and intothe passageway 103 defined by the axially aligned valve stem 100. Theformation fluid flows through the axial path 103 of the valve stem tothe upper end thereof. This upper end extends into the formation fluidsampling reservoir 104 and is formed with radially extending ports 106.The formation fluids flow radially outwardly through the ports 106 andfill the formation fluid sample receiving reservoir I04.

When the sample receiving reservoir 104 has been filled a desiredamount, the explosive squib may be actuated from above so as to open theoverall passageway defined by the passageway segments I32 and 128. Uponexplosively opening this passageway, the radially extending surface 122on the valve stem 100 is acted upon by the high-pressure hydrostaticfluids flowing through the passageways I28 and 132. The force resultingfrom the hydrostatic pressures acting on the ef fective area of theannular surface I22 forces the stem I00 downwardly so that the ports 106are covered by the surface 153 of the mandrel 112 and, thereby, thesample receiving chamber 104 becomes sealed.

As the cylindrical surface 154 clears the large radially extending port152 formed in the mandrel 112, an additional, relatively unobstructedand high-capacity flow of high-pressure hydrostatic or well bore annulusfluid enters the space 111 adjacent the radially extending surface 122.This additional flow through port 152 insures reliable actuation of theslide valve means 100, 108, 106.

As the additional port 156 of the valve stem becomes aligned with theannular space 111, the hydrostatic fluids rush through port 152 andspace 111 to the interior valve stem passageway 103. The hydrostaticfluids then flow downwardly, away from the sample receiving reservoir104, through the adapter member 114 and into the sealing means carriersection 22 of the tool. This continues such that fluids build up in theinterior of member 114 and flow outwardly from the tool and into theperforations within the well casing 12 and formation 14 adjacentthereto.

As the high-pressure hydrostatic fluids flow to the outside of thesealing pads 24 and into the adjacent perforations, the existingpressure differential between the hydrostatic fluids on one side of thesealing pads 24 and the formation fluids on the other side of the padsis eliminated so as to release each seal and enable it to detach fromthe side 13 of the casing 12.

At this point, the overall tool is free to be hoisted to the surface ofthe well site where the plug 1 16 may be threadedly disengaged fromwithin the fluid passageway [23 leading from the upper portion of thesampler reservoir 104 and the formation sample trapped therein may beremoved.

ALTERNATIVE VALVE EMBODIMENT Referring now to FIG. of the drawings, analternative embodiment of the sample chamber closing and differentialpressure equalizing valve of the present invention is shown. This unitwould be substituted for the slide valve mechanism 100-108 previouslydiscussed.

From top to bottom, the housing construction comprises a samplereceiving reservoir 200 threadedly engaged with an adapter member 202 bymeans of male threads 204 formed on the upper portion of the adaptermember and female threads 206 formed on the lower portion of theformation sample reservoir. A valve body section 208 corresponding tothe mandrel 112 of the preferred embodiment is threadedly connected withthe lower end of the adapter member 202 by means of male threading 210on the lower end of the valve body section 208. The lower portion of thevalve body section 208 is connected with an adapter section 214 of theoverall tool, which adapter section 214 corresponds to theadapterportion 114 of the preferred embodiment of the present invention. Thevalve body section 208 is connected to the carrier section 214 by meansof male threads 216 on the lower portion of the valve body and femalethreads 218 formed within the upper portion of the carrier section 214.A valve stem 220, preferably cylindrical in nature, is disposed axiallywithin the overall tool in a passageway 221 defined generally throughoutthe various aforementioned sections of the overall tool.

The valve stem 220 has a configuration similar to that of thecorresponding valve 100 of the preferred embodiment. The valve stem 220is a generally hollow elongated cylindrical member having radiallyextending ports 240 formed at the upper end thereof. A central axialflow path 242 is defined by the internal cylindrical wall 244 of thestem 220, which passageway 242 extends through the lower axial end ofthe stem 220 but is blocked at the upper axial end thereof by radiallyextending wall 243 so that fluid flowing upwardly through the loweraxial end of the passageway 242 of the stem 220 can only escape outthrough the radial ports 240 at the upper end thereof.

A stepped-up, or radially outwardly enlarged, cylindrical portion 246 isformed on the stem 220. The stepped-up portion 246 is formed with anupper radially extending surface 248, a lower radially extending surface250, and a cylindrical outer surface 252.

The valve body section 208 is formed with an axial passageway 254 havinga diameter corresponding to the outside diameter of the built-up portion246 of the valve stem 220. The axial passageway 254 of the valve bodysection 208 near the lower end thereof, is of decreased diameter whichcorresponds with the outside diameter of the nonstepped-up portion ofthe valve stem 220. In this manner, an internal, radially extending, andupwardly facing shoulder 256 is provided which is in abuttingrelationship with the lower radially extending surface 250 on thebuilt-up portion 246 of the valve stem 220 when the valve stem is movedto its lowermost position at its full length of travel. When the valvestem is in its upward position, as shown in FIG. 10, with the radialports 240 thereof extending into the fonnation fluid sampling reservoir200, the upper radially extending surface 248 of the steppedup portion246 of the valve stem 220 is in abutting relationship with the lowerradially extending and downwardly facing portion 258 of the adaptermember 202. Thus it can be seen, that the distance of travel of thevalve stem 220 has an upper limit defined by the radial surface 248 anda lower limit defined by the surface 256.

The adapter member 202 may be provided with a passageway 260 leadingfrom an outside port 261 of the tool, adjacent the high-pressure wellbore fluids downwardly to the upper radially extending surface 248 ofthe built-up portion 246 of the valve stem 220. This passage arrangementis somewhat similar to the arrangement 128/132 shown in the preferredembodiment of the present invention. In FIG. 10, the passageway 160leads from ports 261, outside the tool, to the upper radial surface 248and is blocked by a plug indicated as numeral 262. When an explosivecharge, not shown, is detonated, the plug 262 is removed from the flowpath defined by passageway 260 and high-pressure hydrostatic, well borefluid flows therethrough to assert a force against the upper radiallyextending surface 248 of the built-up portion 246 of the valve stem 220.

This explosive charge may be associated with plug 262 in somewhat thesame manner that charge of the FIG. 8 embodiment is associated with plug134. An electrical function 264, schematically shown in FIG. 10, isassociated with the charge which ruptures plug 262 in much the samemanner that junction 146 of the FIG. 8 embodiment is associated withcharge 140.

The force asserted by the pressure of the hydrostatic well bore fluid onthe area of the radially extending surface 248 is sufi'tcient to movethe cylindrical surface 252 of the builtup portion 246 of the step valve220 downwardly and clear of a plurality of radially extending,supplemental, continuously open ports 266, formed circumferentiallyabout the valve body section 208. As the high-pressure hydrostatic fluidflows inwardly through the radial extending ports 266, which areuniquely resistant to clogging, and acts downwardly upon the upperradially extending surface 248 of the valve stem 220, the movement ofthe valve stem is more reliably actuated and the upper radiallyextending ports 240 are withdrawn from within the formation fluidreceiving chamber 200. The ports 240 are thereby sealed against theinternal cylindrical surface 268 of the adapter member 202. Theformation fluid sample receiving chamber is thereby sealed against theinvasion of well bore fluid and the cylindrical surface of thestepped-up portion 246 of the valve stem 220 is forced downwardly untilthe lower radially extending surface 250 of the stepped-up portion 246of the valve stem 220 comes into abutting engagement with the internalshoulder surface 256 at the lower end of the axial passageway of thevalve body 208.

The sequential two stage" actuation of port means 260 and 266 affordsreliability in operation and minimizes port clogging problems, in amanner akin to the "two stage operation of port means 128/132 and 152.

A cushioning member (not shown) may be disposed between the abuttingsurfaces 250 and 256 of the alternative embodiment and surfaces 124 and126 of the preferred embodiment. The cushioning member may comprise anelastomeric bumper or the like. As will be understood, the space betweensurfaces 250 and 256 will be substantially free of liquid.

A generally axially extending flow path 268 may be formed in the valvebody section 208 to extend from the lowermost terminal portions thereofto an inwardly directed port 270 adjacent the cylindrically extendingsurface 252 of the built-up portion 246 of the valve stem 220, when thevalve is in the raised position of FIG. 10. When the lower radiallyextending surface 250 of the built-up portion 246 is in abuttingrelationship with the internal shoulder 256 of the valve body 208, theport 270 communicates with the radial ports 266 through an annular spaceleft as the upper portion of the cylindrical surface 252 clears the port270.

As the built-up portion 246 of the valve stem 220 moves to its lowennostposition under the influence of hydrostatic fluids entering through theradial port 266, an equalizing flow path is formed for the well fluids,extending through the radial ports 266 of the valve body and into thegenerally axially extending flow path 268 leading out to the lowerterminal end of the valve body. In this manner, high-pressurehydrostatic fluid is directed through the member 214 and into thecarrier member 22 upon which sealing pads are mounted and adiacent whichthe perforation sites are disposed. The high-pressure hydrostaticannular fluids then pass into the perforation site and operate toeliminate the pressure differential across the sealing pads so as torelease the sealing cup effect on each sealing pad in the same manner asdiscussed with respect to preferred embodiment of the present invention.Upon release of the sealing pads, the alternative embodiment of thetester tool of the present invention may be cable or wire line hoistedout from the well bore.

A generally axially extending passageway 272 may be formed in the upperadapter member 202 to extend downwardly from the interior of thehydraulic fluid sampler chamber 200 to a radially extending port 274formed from the lower end of the generally axially extending passageway272 to the outer surface of the adapter member 202. A plug member 276may be threadedly engaged within the radially extending passageway 274and may be removed by any appropriate tool at the surface of the wellsite or a laboratory so as to permit the withdrawal of the formationfluid trapped within the formation sampler reservoir 200.

It may be found, that under adverse conditions a pressure buildup mayoccur in the carrier section and force the stem 120 upward, as a pistonwould be moved in a cylinder, so as to reexpose the radial extendingports 240 to the interior of the formation fluid sampler reservoir 200.This piston effect may be avoided by the provision of an automatic latchmeans feature in which a spring loaded latch member 278 may be providedwithin the valve body. This latch would operate to engage an annulargroove 280 formed on the lower axial end of the valve stem 220 when thestem is moved to its lowermost position under the influence of thehigh-pressure annular hydrostatic fluid.

For example, if the perforated portion 70 of stud 68 and flow path 268where to become clogged, gas pressure might be generated in the carriersection 22 as a result of detonation of the shaped charges. Thispressure might be such that, lacking the restraining influence of thehydrostatic or well bore pressure acting on piston 146, would besufficient to induce upward or reopening movement of the valve stem 220.Under such circumstances, valve opening movement of stem 220 would occuras the tool was raised through the well bore, since the hydrostatic wellbore pressure would progressively diminish to zero during the raisingoperation. Thus, the latch mechanism 2'78 would tend to act to preventsuch upward valve stem movement.

ADDITIONAL FEATURES Referring briefly now to FIGS. 4 and 9, anadditional feature is shown which may be incorporated in either thepreferred or alternative embodiment of the present invention.

Referring to the preferred embodiment, if for any reason it should bedesired at the well head or at a laboratory to move the valve stem I00of FIG. 4 upwardly, this may be accomplished by pumping a hydrostaticfluid through passageway 300 which extends in a radial plane containingcross-sectional line 9-9. As shown in FIGS. 4 and 9, a generally axiallyextending passageway 302 extends from the inner terminal end ofpassageway 300 and into the annular space 111. A plug member 304 may bethreadedly engaged within the passageway 300 to block the flow of anyfluid therethrough.

in order to force the stem upwardly, the plug 304 is threadedlydisengaged from within the passageway 300 and hydrostatic fluids arepumped in through the passageway 300, up through the passageway 302, andagainst the lower radially extending surface 124 of the built-up portion108 of the valve stem 100.

SUMMARY OF THE ADVANTAGES OF THE INVENTION It can thus be seen that aformation fluid testing tool has been herein provided, which tool iscompact and may be hoist lowered into a well bore.

The operation of slide valve mechanism housed within the tool may beinitiated by a very small explosive charge or even by an impulse ofenergy applied to the tool either hydraulically or pneumatically. Theslide valve mechanism sequentially and under positive control, performsthe functions of sealing the formation fluid receiving chamber andeliminating the pressure differential between the interior of the tooland the ambient hydrostatic annular fluids surrounding the tool.

As a result of the dual function capacity of the single acting slidevalve, the overall tool is less complicated and has fewer moving partsthan prior equipment.

As a corollary to the noncomplicated nature of the preferred embodiment,tester tools embodying the present invention are less expensive to buildand have a reduced chance of jamming due to the infiltration of sand ordetritus into the moving parts thereof. Only a minimal charge need beused as an energy source for moving the valve mechanism as the ambienthydrostatic annular fluid pressure is utilized as the main power sourcefor operating the valve.

The internal flow path configuration made possible by the efficientnature of the present invention, and particularly the preferredembodiment, permits the incorporation of formation fluid passagewayshaving larger diameters than currently possible. These large diameterflow paths. in turn, further reduce the chances of the formation fluidpassageway being blocked by sand and detritus.

The simple and reliable operation of the slide valve made possible bythe sequentially operable or "two stage" porting, is virtually foolproofso as to insure that the sample retained within the sample receivingchamber is uncontaminated by the annular fluids surrounding the tool andrelease of the sealing pads occurs.

The cumulative effect of all the aforementioned advantages is thattester tools made in accordance with the present invention are moreversatile, and more reliable than prior devices which have heretoforebeen known.

While what has been shown in the drawing and described in the detaileddescription is a preferred embodiment and an alternative embodiment ofthe present invention, it is of course understood that variousmodifications and changes may be made therein without departing from theinvention and it is therefore intended to cover in the appended claimsall such modifications and changes as may fall within the true spiritand scope of the present invention.

What I claim is:

1. Apparatus for obtaining formation fluids from well bores comprising:

formation fluid receiving means;

formation perforating means;

fluid passageway means operable to define a flow path leading from aformation perforation to said formation fluid receiving means;

sealing means for isolating said flow path; and

unitary valve means for sequentially closing said isolated flow path tosaid formation fluid receiving means and for releasing said sealingmeans in response to a continued, unidirectional valving movement ofsaid valve means; and

said valve means being movable centrally and longitudinally of saidapparatus and contains a relatively large, longitudinally extendingpassageway defining a portion of said fluid passageway means leadingfrom said formation perforation to said formation fluid receiving means.

2. An apparatus according to claim 1 wherein said valve means is poweredby pressure applied thereto by well bore fluid dispose the well andambient to said apparatus, with said pressure being transmitted, insequence. through larger passage means during movement of said valvemeans.

3. An apparatus according to claim I:

wherein said valve an elongated valve stem having said longitudinallyextending passageway; and

wherein said apparatus includes a plurality of sequentially openablepassage means operable to transmit well bore pressure to said valvemeans and induce movement thereof.

4. An apparatus according to claim 3 with:

said valve stem being generally cylindrical in configuration and havinga cylindrical wall portion;

a first axial end of said valve stem being formed with a wall extendingradially across said longitudinally extending passageway;

said radially extending wall being operable to prevent the passage offluids through said first axial end of said valve stem;

a second axial end of said valve stem being open so as to permit theflow of fluids into or out from said longitudinally extending passagewayof said valve stem through said second axial end;

first generally radially extending port means being formed in saidcylindrical wall portion of said valve stem adjacent said first axialend of said stern, said port means being adapted to transmit well borefluid to said formation fluid receiving means; and

second generally radially extending, equaling port means formed in saidcylindrical wall portion and in continuous communication with saidlongitudinally extending passageway, said second port means beingadapted to transmit the pressure of well bore fluid to said sealingmeans to effect the release thereof.

5. An apparatus according to claim 4 wherein:

said first generally radially extending port means in said valve stem isdisposed in fluid flow communicating relation with the interior of saidformation fluid receiving means for the filling of said formation fluidreceiving means with formation fluids;

said valve stem is formed with an outer, radially outwardly enlargedcylindrical portion having first and second radially extending surfaceareas formed at each axial end thereof;

said apparatus is provided with a valve body for supporting said valvestem;

a first fluid passageway means in said valve body extends from well borefluid surrounding the overall apparatus to said first radially extendingsurface area formed on said outer cylindrical portion of said valvestem;

a plug means is disposed within said first valve body fluid passagewaymeans;

said apparatus includes means for imparting an impulse of energy to saidplug means to rupture said plug means;

the rupturing of said plug member is operable to direct said well borefluid to said first radially extending surface of said outer cylindricalportion of said valve stem through said first fluid passageway means;and

an axial force is developed on said valve stem by said well bore fluidacting on said first radially extending surface of said stepped-upportion, said axial force being operable to slide said valve stemaxially away from said formation fluid receiving means whereby saidfirst radially extending port means formed in said valve stem iswithdrawn from fluid flow communicating relation with the interior ofsaid formation fluid receiving means, and said formation fluid receivingmeans is sealed from said isolated flow path to said formationperforation by said radially extending wall disposed across said firstaxial end of said longitudinally extending passageway through said valvestem.

6. An apparatus according to claim 5 wherein:

said valve body is formed with second fluid passageway means in saidvalve body and operable to extend from the well bore fluid surroundingthe overall apparatus to said cylinder portion formed on said valvestem;

said second fluid passageway means is spaced longitudinally of said stemfrom the said first fluid passageway means by an increment of axialdistance;

the movement of said valve stem through said last mentioned increment ofaxial distance in response to the well bore fluid passing through saidfirst fluid passageway means and acting against said first radiallyextending surface on said cylindrical portion of said stern beingoperable to expose said first radially extending surface on saidcylindrical portion of said valve stem to said second fluid passagewaymeans to direct additional well bore fluid against said first radiallyextending surface.

7. An apparatus according to claim 6 wherein:

said second radially extending port means is operable to place said wellbore fluid in fluid flow communicating relation with said longitudinallyextending fluid passageway defined through the interior of said stemwhen said stem is moved a sufficient axial distance to withdraw saidfirst port means from flow communicating relation with said formationfluid receiving chamber 8. An apparatus according to claim 7 wherein:

an annular space is formed in said valve body about said stem when saidcylindrical portion of said stem is moved in a direction away from saidformation fluid receiving means; and

one axial end of said annular space is defined by said first radiallyextending surface of said cylindrical portion of said valve stem.

9. An apparatus according to claim 3 with:

said valve stem being generally cylindrical in configuration and havinga cylindrical wall portion;

a first axial end of said valve stem being formed with a wall extendingradially across said longitudinally extending passageway;

said radially extending wall being operable to prevent the passage offluids through said first axial end of said valve stem;

at second axial end of said valve stem being open so as to permit theflow of fluids into or out from said longitudinally extending passagewayof said valve stem through said second axial end;

first generally radially extending port means being formed in saidcylindrical wall portion of said valve stem adjacent said first axialend of said stern, said port means being adapted to transmit well borefluid to said formation fluid receiving means; and

equalizing port means formed in a valve body surrounding said valve stemand in continuous communication with said longitudinally extendingpassageway, said equalizing port means being adapted to transmit thepressure of well bore fluid to said sealing means in response to aterminal movement of said valve stem; and latch means operable to engageand secure said valve stem subsequent to said terminal movement.

10. Apparatus for obtaining formation fluids from well bores comprising:

formation fluid receiving means;

formation perforating means;

fluid passageway means for defining a flow path from a for mationperforation to said formation fluid receiving means;

sealing means for isolating said flow path; unitary valve means forsequentially closing said isolated flow path to said formation fluidreceiving means and for releasing said sealing means in response to acontinued, unidirectional valving movement of said valve means; saidvalve means comprising an elongated valve stem having a longitudinallyextending passageway formed therethrough; said londtudinally extendingpassageway formed in said stem comprising a portion of said fluidpassageway means leading from said formation perforation to saidformation fluid receiving means; and a plurality of sequentiallyopenable passage means operable to transmit well bore pressure to saidvalve means and induce movement thereof, with the first operable one ofsaid passage means being opened in response to the detonation ofexplosive means, and a later operable one of said passage means beinglarger in flow capacity than said first operable one of said passagemeans and continuously in communication with the exterior of said tool.

11. An apparatus according to claim 10 wherein an additional passagewayis provided which communicates with said valve means and is operable tobe connected with a source of pressurized fluid whereby hydraulic fluidmay be forced inwardly through said additional passageway and bedirected against said stem to force said stem toward said formationfluid receiving chamber and cause said stem to open a portion of saidisolated flow path and permit fluid to move out of said formation fluidreceiving means.

12. An apparatus according to claim 10 with the addition of latch means;

said latch means operable to lock said valve means in a position wheresaid isolated flow path is closed and said sealing means are released.

1. Apparatus for obtaining formation fluids from well bores comprising:formation fluid receiving means; formation perforating means; fluidpassageway means operable to define a flow path leading from a formationperforation to said formation fluid receiving means; sealing means forisolating said flow path; and unitary valve means for sequentiallyclosing said isolated flow path to said formation fluid receiving meansand for releasing said sealing means in response to a continued,unidirectional valving movement of said valve means; and said valvemeans being movable centrally and longitudinally of said apparatus andcontains a relatively large, longitudinally extending passagewaydefining a portion of said fluid passageway means leading from saidformation perforation to said formation fluid receiving means.
 2. Anapparatus according to claim 1 wherein said valve means is powered bypressure applied thereto by well bore fluid dispose the well and ambientto said apparatus, with said pressure being transmitted, in sequence,through larger passage means during movement of said valve means.
 3. Anapparatus according to claim 1: wherein said valve an elongated valvestem having said longitudinally extending passageway; and wherein saidapparatus includes a plurality of sequentially openable passage meansoperable to transmit well bore pressure to said valve means and inducemovement thereof.
 4. An apparatus according to claim 3 with: said valvestem being generally cylindrical in configuration and having acylindrical wall portion; a first axial end of said valve stem beingformed with a wall extending radially across said longitudinallyextending passageway; said radially extending wall being operable toprevent the passage of fluids through said first axial end of said valvestem; a second axial end of said valve stem being open so as to permitthe flow of fluids into or out from said longitudinally extendingpassageway of said valve stem through said second axial end; firstgenerally radially extending port means being formed in said cylindricalwall portIon of said valve stem adjacent said first axial end of saidstem, said port means being adapted to transmit well bore fluid to saidformation fluid receiving means; and second generally radiallyextending, equaling port means formed in said cylindrical wall portionand in continuous communication with said longitudinally extendingpassageway, said second port means being adapted to transmit thepressure of well bore fluid to said sealing means to effect the releasethereof.
 5. An apparatus according to claim 4 wherein: said firstgenerally radially extending port means in said valve stem is disposedin fluid flow communicating relation with the interior of said formationfluid receiving means for the filling of said formation fluid receivingmeans with formation fluids; said valve stem is formed with an outer,radially outwardly enlarged cylindrical portion having first and secondradially extending surface areas formed at each axial end thereof; saidapparatus is provided with a valve body for supporting said valve stem;a first fluid passageway means in said valve body extends from well borefluid surrounding the overall apparatus to said first radially extendingsurface area formed on said outer cylindrical portion of said valvestem; a plug means is disposed within said first valve body fluidpassageway means; said apparatus includes means for imparting an impulseof energy to said plug means to rupture said plug means; the rupturingof said plug member is operable to direct said well bore fluid to saidfirst radially extending surface of said outer cylindrical portion ofsaid valve stem through said first fluid passageway means; and an axialforce is developed on said valve stem by said well bore fluid acting onsaid first radially extending surface of said stepped-up portion, saidaxial force being operable to slide said valve stem axially away fromsaid formation fluid receiving means whereby said first radiallyextending port means formed in said valve stem is withdrawn from fluidflow communicating relation with the interior of said formation fluidreceiving means, and said formation fluid receiving means is sealed fromsaid isolated flow path to said formation perforation by said radiallyextending wall disposed across said first axial end of saidlongitudinally extending passageway through said valve stem.
 6. Anapparatus according to claim 5 wherein: said valve body is formed withsecond fluid passageway means in said valve body and operable to extendfrom the well bore fluid surrounding the overall apparatus to saidcylinder portion formed on said valve stem; said second fluid passagewaymeans is spaced longitudinally of said stem from the said first fluidpassageway means by an increment of axial distance; the movement of saidvalve stem through said last mentioned increment of axial distance inresponse to the well bore fluid passing through said first fluidpassageway means and acting against said first radially extendingsurface on said cylindrical portion of said stem being operable toexpose said first radially extending surface on said cylindrical portionof said valve stem to said second fluid passageway means to directadditional well bore fluid against said first radially extendingsurface.
 7. An apparatus according to claim 6 wherein: said secondradially extending port means is operable to place said well bore fluidin fluid flow communicating relation with said longitudinally extendingfluid passageway defined through the interior of said stem when saidstem is moved a sufficient axial distance to withdraw said first portmeans from flow communicating relation with said formation fluidreceiving chamber.
 8. An apparatus according to claim 7 wherein: anannular space is formed in said valve body about said stem when saidcylindrical portion of said stem is moved in a direction away from saidformation fluid receiving means; and one axial end of said annular spaceis defined by said first radially extending surface of said cylindricalportion of said valve stem.
 9. An apparatus according to claim 3 with:said valve stem being generally cylindrical in configuration and havinga cylindrical wall portion; a first axial end of said valve stem beingformed with a wall extending radially across said longitudinallyextending passageway; said radially extending wall being operable toprevent the passage of fluids through said first axial end of said valvestem; a second axial end of said valve stem being open so as to permitthe flow of fluids into or out from said longitudinally extendingpassageway of said valve stem through said second axial end; firstgenerally radially extending port means being formed in said cylindricalwall portion of said valve stem adjacent said first axial end of saidstem, said port means being adapted to transmit well bore fluid to saidformation fluid receiving means; and equalizing port means formed in avalve body surrounding said valve stem and in continuous communicationwith said longitudinally extending passageway, said equalizing portmeans being adapted to transmit the pressure of well bore fluid to saidsealing means in response to a terminal movement of said valve stem; andlatch means operable to engage and secure said valve stem subsequent tosaid terminal movement.
 10. Apparatus for obtaining formation fluidsfrom well bores comprising: formation fluid receiving means; formationperforating means; fluid passageway means for defining a flow path froma formation perforation to said formation fluid receiving means; sealingmeans for isolating said flow path; unitary valve means for sequentiallyclosing said isolated flow path to said formation fluid receiving meansand for releasing said sealing means in response to a continued,unidirectional valving movement of said valve means; said valve meanscomprising an elongated valve stem having a longitudinally extendingpassageway formed therethrough; said longitudinally extending passagewayformed in said stem comprising a portion of said fluid passageway meansleading from said formation perforation to said formation fluidreceiving means; and a plurality of sequentially openable passage meansoperable to transmit well bore pressure to said valve means and inducemovement thereof, with the first operable one of said passage meansbeing opened in response to the detonation of explosive means, and alater operable one of said passage means being larger in flow capacitythan said first operable one of said passage means and continuously incommunication with the exterior of said tool.
 11. An apparatus accordingto claim 10 wherein an additional passageway is provided whichcommunicates with said valve means and is operable to be connected witha source of pressurized fluid whereby hydraulic fluid may be forcedinwardly through said additional passageway and be directed against saidstem to force said stem toward said formation fluid receiving chamberand cause said stem to open a portion of said isolated flow path andpermit fluid to move out of said formation fluid receiving means.
 12. Anapparatus according to claim 10 with the addition of latch means; saidlatch means operable to lock said valve means in a position where saidisolated flow path is closed and said sealing means are released.